Inspection tool for detecting cracks in jet pump beams of boiling water

Abstract

An integrated apparatus for inspecting the arms of jet pump beams using eddy current technology, while also scanning the borehole region using ultrasound technology. In order to inspect the jet pump beam arms, a special scanner is required to properly move an eddy current coil in two dimensions over the complex machined surface on top of the arms. The scanner has two axes of motion and can perform a raster scan in either direction. The inspection payload, an eddy current probe, moves the length of the scanning axis and then the payload is indexed (i.e., moved a small distance) along the indexing axis. The payload is then moved smoothly back along the length of the scanning axis. Data is collected only during motion along the scanning axis. The scanner has a unique curved track design for maintaining the orientation of the eddy current probe perpendicular to the inspection surface. It allows inspecting the top flat surface and the curved edges of the jet pump beams. The eddy current probe is mounted on a movable carriage which rolls along the curved track via two wheels which move along two different curves having the same radius, but different arc lengths.